The invention provides an algorithm for implementing global navigation satellite system (GNSS) and WIFI system seamless vertical handoff based on a fuzzy neural network algorithm in order to realize a purpose of fusing two different positioning systems mutually to implement seamless handoff of indoor and outdoor positioning and navigation. The algorithm comprises the following steps: acquisition of main positioning information, handoff triggering based on received signals, and handoff algorithm judgment based on fuzzy neural network control. The algorithm for implementing the GNSS and WIFI system seamless vertical handoff has the beneficial effect of overcoming a defect that WIFI position precision is reduced outdoor and GNSS signals have a possible of occurring interruption indoor so as to provide wrong positioning information for a user; America GPS, Russia Glonass, EU Galileo and China Beidou satellite have a large development on satellite positioning and navigation application technology positioning aspects indoor, outdoor, underground, on the earth surface and the like; and meanwhile, the algorithm provided by the invention has wide applications in the fields of national military applications, international counter terrorism, tunnel detection and the like.